The announcement came today at a scientific conference attended by about a thousand biodefense experts in Washington, D.C., that was organized by the American Society of Microbiology. One of the scientists who did the work, Ron Fouchier of Erasmus Medical Center, spoke at the conference and presented data suggesting that the mutant virus created in his lab was not as dangerous as has been presented in media reports.

"Certainly, this would not be a virus that would kill half of the world population, as we've seen in the lay press time and time again. That is clearly, clearly wrong," said Fouchier.

The experiments involved the potentially lethal H5N1 bird flu virus and showed which genetic changes could make the virus spread through the air between ferrets — the laboratory stand-in for people.

Late last year, in an unprecedented move, the National Science Advisory Board for Biosecurity reviewed the work and recommended not publicly publishing the details of how these altered viruses were created, so as not to publish a recipe that could be misused by someone seeking to create a dangerous, contagious virus.

But earlier this month, the World Health Organization convened a different panel, mostly composed of international flu experts, that came to the opposite conclusion. It said the experiments were important for public health efforts to prepare for a possible future pandemic, and that they should be published openly.

Fouchier emphasized that in his studies, ferrets did not die after getting the virus from the sneezes and coughs of other ferrets. "Certainly, if the ferrets receive virus via aerosol route, we have never seen severe disease in the ferrets," he said, although the virus could be highly lethal if administered at high doses directly into the respiratory tract of ferrets. He added that pre-exposure to seasonal flu seems to offer protection from severe disease.

Anthony Fauci, head of the National Institute of Allergy and Infectious Diseases, said the government will ask the NSABB to review new versions of both scientific manuscripts in a meeting that could happen as early as March, depending on people's schedules. He said the discussion would cover new data and "re-clarification" of old data, so that the members of the NSABB would have the opportunity to see the same information as the WHO panel.

Paul Keim, acting chairman of the NSABB, said "new data is always good. We're scientists; we love data." But he said until the committee has seen the data, it's impossible to say if it could change their views on whether to publish the work.

"The board has always said that our recommendations were the first step in this process and that we were, if anything, just putting out an alert that this is an area of great concern that needs to be looked at very closely by a broad spectrum of people," Keim noted.

Another member of the NSABB, Michael Osterholm of the University of Minnesota, said the committee's initial recommendations came after hundreds of hours of conference calls that took place over two months. "To say that this was in-depth would not do it justice," said Osterholm, who noted that the recommendations were unanimous.

He noted that one of the primary concerns of the committee was the ability of the researchers to change a flu virus in ways that made it readily transmissible between mammals.

"As we've tried to make clear from the very beginning, the virulence of virus, the ability of it to kill, is not central to our deliberations," said Osterholm. "Because we know that what happens in ferrets may not predict what will happen in terms of virulence in humans."

The committee had recommended that sensitive details of the experiments be made available to legitimate scientists around the world through some sort of secure communications process. Government officials have been working hard to create such a system, but it's proving legally to be no easy matter. And some researchers say any attempts to keep the information under wraps would be futile anyway.

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Transcript

ROBERT SIEGEL, HOST:

The scientific community remains divided over recent experiments over the bird flu virus. Critics say the research created mutant viruses that could cause a dangerous pandemic in people if they got out of the lab. And experts can't agree on whether details of the work should be made public.

NPR's Nell Greenfieldboyce reports that today the scientists at the center of the controversy tried to clear up some misconceptions.

NELL GREENFIELDBOYCE, BYLINE: At seven o'clock this morning, a ballroom at a fancy hotel in Washington, D.C. was crowded with scientists. They were attending a meeting organized by the American Society for Microbiology, and everyone had woken up early to see a presentation by Ron Fouchier. He's a virologist at Erasmus Medical Center in the Netherlands.

For months, a mutant virus created in his lab has been in the headlines. Some experts say a release of this virus could be catastrophic. But Fouchier doesn't see it that way.

DR. RON FOUCHIER: Certainly, this would not be a virus that would kill half of the world population, as we've seen in the lay press time and time again. That is clearly, clearly wrong.

GREENFIELDBOYCE: His lab created the modified virus as part of its research on the bird flu virus, H5N1. H5N1 circulates in birds out in the wild. People rarely get it but when they do they often die. So far, six people haven't been contagious, but public health experts fear the virus might naturally evolve and start spreading like regular flu.

Fouchier wanted to see if that was a real possibility. His experiment showed that certain genetic changes did make the virus spread through coughs and sneezes, at least in ferrets and ferrets are the laboratory stand-in for people. But Fouchier says it did not seem to spread very easily.

FOUCHIER: And so, to then extrapolate that this virus would spread like wildfire in humans is really, really far-fetched at this stage.

GREENFIELDBOYCE: He said the virus could be lethal if high doses were put directly into the animals' respiratory tract. But ferrets who got the virus from the coughing or sneezing of other ferrets did not die.

FOUCHIER: If the ferrets received virus via aerosol route, we have never seen severe disease in the ferrets.

GREENFIELDBOYCE: Fouchier could not go into many details about his work. It hasn't yet been published in a science journal and publication is in limbo. That's because of the conflicting recommendations of two high profile committees. One of them advises the U.S. government on biology that could be misused. It said some parts of this work should be kept secret so the recipe will not fall into the wrong hands.

But now, government officials want that committee to take another look because, two weeks ago, an expert panel convened by the World Health Organization came to a different conclusion. It called for full publication, saying this research will help public health efforts to prepare for a possible pandemic if the bird flu virus mutates in the wild.

Michael Osterholm is an infectious disease expert with the University of Minnesota who serves on the committee that wanted to keep some details under wraps. He says it's impossible to predict if that group will see things differently this time around.

MICHAEL OSTERHOLM: I can't prejudge that. We really need to wait and see what other information might be provided. I know with great confidence that the entire board will come with an open mind, but based on a set of scientific principles, and we'll look at it again.

GREENFIELDBOYCE: That reassessment may come as soon as next month. For now, researchers around the world have put a voluntary moratorium on all work with these viruses.